Skip to content

Uh-oh, it looks like some (many?) new or fairly new kitchen cabinets are outgassing several types of PCBs from the wood sealants used on the cabinets. PCBs (polychlorinated biphenyls) were banned in the 1970s due to health risks - for example, they are known carcinogens, and some are neurotoxic (also here).

Researchers from the University of Iowa monitored air inside and outside 16 Iowa homes and found 3  types of PCBs (PCB-47, PCB-51, and PCB-68) wafting off the finished kitchen cabinets. They suggest that the PCBs becoming airborne are "unintentional impurities", that is, inadvertent byproducts of polymer sealants (from the common ingredient 2,4-dichlorobenzoyl peroxide) used in modern kitchen cabinetry. They found that unfinished cabinets had no PCB emissions. The concentrations seemed to be dependent on the year the house was built - with higher levels in houses built in the past 5 years (one house had just been completed),  and also in a recently remodeled kitchen (new cabinets!). The cabinets were made by different manufacturers.

So now we have a new source of indoor air pollution to think about. The big questions are: 1) What, if anything, does this mean for human health? 2) How long does this outgassing from sealants go on for? 3) Are there alternative sealers that don't have this problem? By the way, the researchers discuss that household paints emit PCBs (such as PCB 11) as byproducts of paint pigment manufacturing, and yes, they were found both inside and outside houses. We love our plastics, use them in so many products, but there are consequences. From Env. Health News:

Finished kitchen cabinets are emitting toxic PCBs

Researchers tested indoor air at 16 homes and found three types of PCBs are widespread, and finished cabinets are the source of the toxics, according to a study released today. They suspect the PCBs [polychlorinated biphenyls] are byproducts of sealants used on the cabinets. The study, from the University of Iowa, is the first to suggest wood finishing products are a significant source of PCBs to indoor air and finds that, despite federal bans on PCBs, the chemicals are still being released into the environment, including our homes.  ...continue reading "Kitchen Cabinet Sealants Can Be A Source of Indoor Air Pollution"

This post is about an issue that I've covered before - the issue of unnecessary medical tests and care, which has been documented by many, especially Dr. H. Gilbert Welch (here and here). In the past I've focused on research documenting physical and emotional harms resulting from overuse of some medical tests and procedures, especially some types of cancer screening, but today's post is about the financial harms of unnecessary medical tests and procedures.

We're talking about medical tests or services that are overused, perhaps done "routinely" when there are no symptoms or real reasons to do the test. The cost of unnecessary tests and services can be financially devastating to the person receiving the bill(s). But this "waste" has also been estimated  at $765 billion a year by the National Academy of Medicine. This is about a fourth of all the money spent each year on health care! Wow. The following article by Marshall Allen is co-published on both ProPublica and NPR. Excerpts from NPR:

Unnecessary Medical Care: More Common Than You Might Imagine

It's one of the intractable financial boondoggles of the U.S. health care system: Lots and lots of patients get lots and lots of tests and procedures that they don't need. Women still get annual cervical cancer testing even when it's recommended every three to five years for most women. Healthy patients are subjected to slates of unnecessary lab work before elective procedures. Doctors routinely order annual electrocardiograms and other heart tests for people who don't need them.

That all adds up to substantial expense that drives up the cost of care for all of us. Just how much, though, is seldom tallied. So, the Washington Health Alliance, a nonprofit dedicated to making care safer and more affordable, decided to find out. The group scoured the insurance claims from 1.3 million patients in Washington state who received one of 47 tests or services that medical experts have flagged as overused or unnecessary. What the group found should cause both doctors, and their patients, to rethink that next referral. In a single year:

  • More than 600,000 patients underwent a treatment they didn't need, treatments that collectively cost an estimated $282 million.
  • More than a third of the money spent on the 47 tests or services went to unnecessary care.
  • 3 in 4 annual cervical cancer screenings were performed on women who had adequate prior screenings – at a cost of $19 million.
  • About 85 percent of the lab tests to prep healthy patients for low-risk surgery were unnecessary — squandering about $86 million.
  • Needless annual heart tests on low-risk patients consumed $40 million.

Susie Dade, deputy director of the alliance and primary author of the report released Thursday, said almost half the care examined was wasteful. Much of it comprised the sort of low-cost, ubiquitous tests and treatments that don't garner a second look. But "little things add up," she said. "It's easy for a single doctor and patient to say, 'Why not do this test? What difference does it make?'"

ProPublica has spent the past year examining how the American health care system squanders money, often in ways that are overlooked by providers and patients alike. The waste is widespread – estimated at $765 billion a year by the National Academy of Medicine, about a fourth of all the money spent each year on health care.

Dr. H. Gilbert Welch, a professor at The Dartmouth Institute who writes books about overuse, said the findings come back to "Economics 101." The medical system is still dominated by a payment system that pays providers for doing tests and procedures. "Incentives matter," Welch said. "As long as people are paid more to do more they will tend to do too much."

I recently read a nice article discussing indoor air pollution, which can be worse than outdoor air, even that of cities. Yes, that's true! In past posts I've discussed problems (and health issues) with air fresheners, fragrances, incensedryer sheets, scented candles, synthetic rugs, "stain-proofing", and flame retardants in upholstery, but this article is about furniture and how it can emit various chemicals ("outgassing"), especially when new. Think of all the stains, glues, paints, etc. used in making furniture.

The article points out that when buying new furniture, can look to see if it is certified by Greenguard or SCS Global Services as having low or no emissions of  hazardous chemicals. Another thing to do is avoid particle boardengineered wood, or pressed wood (frequently emits formaldehyde, a carcinogen). But in the mean time - it's generally a good idea to frequently get fresh air in your residence by opening windows for a while. Excerpt's from E. Leamy's article in the Washington Post:

Your furnishings could be causing indoor air pollution

We feel safe in our homes, but that can be a false sense of security. The threat I’m talking about is something we can’t see: indoor air pollution. The air in our homes and workplaces can be more polluted than outdoor air in the most industrialized citiesaccording to the Environmental Protection Agency. The EPA says the problem is compounded by the fact that Americans spend 90 percent of their time indoors. Many different things can cause indoor air pollution, and they have a cumulative effect on our health.

Let’s look at one of those possible sources: our furnishings. Yes, your new carpet or cabinet could be subtly poisoning you with chemicals such as benzene, ethylene glycol or formaldehyde. It’s called “off-gassing.” Four of the top 10 chemicals emitted from furnishings are considered “acute” hazards, or irritants. “Poor indoor air quality can cause or contribute to the development of infections, lung cancer and chronic lung diseases such as asthma,” according to the American Lung Association.

How do researchers know that some furnishings emit harmful gaseous chemicals? Greenguard, a division of UL Environment, has developed a way of testing furniture to find out. In a ­generic-looking office park outside Atlanta, researchers heft furniture into giant, airtight chambers. .... Greenguard developed the testing method so manufacturers who wanted to sell low-emission furniture could prove their products were healthier. UL awards its Greenguard certification to furniture that emits low or no levels of hazardous chemicals

Manufacturers don’t have to state what chemicals they use in their furnishings. The EPA singles out engineered wood — otherwise known as particleboard — as being particularly prone to emitting formaldehyde, a probable carcinogen. UL Environment adds that products that are applied wet, such as glues and paints, often off-gas while they are curing. Sometimes a strong industrial odor is a good hint that a piece of furniture is emitting chemicals. If you develop a headache while inside a building where paints, stains or glues are being used, that’s another clue. 

However, it is possible to know whether harmful chemicals are not present, because more and more furnishings are being certified as having low emissions. Here are certifications you can look for and other steps you can take to reduce your exposure to indoor air pollution from your furnishings: 

1. Check certifications. Look for an indoor-air-quality certification, such as the one offered by Greenguard. Another firm that certifies low-emission furniture is SCS Global Services2. Air out. .... 3. Paint first. If you’re renovating your house, paint it and air it out before installing carpeting and curtains, because they can absorb chemical fumes from the paint..... 4. Buy used. Off-gassing diminishes over time, so buying older furniture can be better. ....5. Avoid particleboard. This material is also called pressed wood, engineered wood and MDF. The glues used to hold the material together often contain harmful chemicals such as formaldehyde. Alternatively, look for certified particleboard products. 6. Choose unscented. .... 7. Beyond furnishings. Other products frequently used in homes can also off-gas and cause indoor air pollution. 

The words and phrases science-based, evidence-based, fetus, and vulnerable are all important words in science and medicine, and are frequently used on this site when I post about new health studies. Medical treatment is based on science, and it is evidence-based (that's why studies are done - to test hypotheses, and to see what the evidence shows). The effects of viruses (e.g. Zika virus, measles), nutrition, and environmental pollutants (e.g. BPA, lead, mercury, pesticides, air pollution) all have effects on the developing fetus. Fetuses, children, the elderly, and immunocompromised individuals are all especially vulnerable to the effects from pollutants. See how important and powerful those words are?

The Washington Post reported Friday (December 15, 2917) that the Trump administration is prohibiting officials at the Centers for Disease Control and Prevention (CDC) from using a list of 7 words or phrases in official documents when preparing next year's budget proposals. The seven words are: science-based, evidence-based, fetus, vulnerable, diversity, transgender, and entitlement.

The CDC is the nation's top health agency and staffed with many scientists working on diseases throughout the world, including the Zika virus (which has an effect on the developing fetus),  and working on ways to prevent sexually transmitted diseases among transgender people. This is an agency with more than 12,000 employees and a $7 billion budget that works on all sorts of health issues - including food and water safety, heart disease and cancer, antibiotic resistance, and censorshipways to prevent epidemics. Their work is based on science, and it looks at all the evidence. Yup - those pesky words are an integral part of the function of the CDC, and of science..

Of course scientists are outraged by this censorship of science. So should you.

Great news coffee drinkers! Another study - this time a large analysis of over 200 studies found that coffee consumption is linked to many health benefits. The best results were from drinking 3 to 4 cups of coffee daily (as compared to none), with a reduction in "all cause" mortality (death from any cause), and cardiovascular disease and death. They also found a lower risk of cancer in general, and with a lower risk of several specific cancers (endometrial, prostate, melanoma, non-melanoma skin cancer, liver cancer) and neurological (Parkinson's disease, Alzheimer's disease, and depression), metabolic (including type 2 diabetes, metabolic syndrome), and liver conditions.

However, during pregnancy high coffee consumption (as compared to low or no consumption) was associated with low birth weight, preterm birth in the first and second trimester, and pregnancy loss. The researchers also found an association between coffee drinking and a small risk of fracture in women, but not in men. Decaffeinated coffee seemed to have many of the same benefits as caffeinated coffee - especially at 2 to 4 cups a day.

The researchers point out in the study (published in The BMJ) that: "Roasted coffee is a complex mixture of over 1000 bioactive compounds, some with potentially therapeutic antioxidant, anti-inflammatory, antifibrotic, or anticancer effects that provide biological plausibility for recent epidemiological associations. Key active compounds include caffeine, chlorogenic acids, and the diterpenes, cafestol and kahweol." Impressive. [All posts about coffee.] From Science Daily:

Three to four cups of coffee a day linked to longer life

Drinking coffee is "more likely to benefit health than to harm it" for a range of health outcomes, say researchers in The BMJ today. They bring together evidence from over 200 studies and find that drinking three to four cups of coffee a day is associated with a lower risk of death and getting heart disease compared with drinking no coffee. Coffee drinking is also associated with lower risk of some cancers, diabetes, liver disease and dementiaHowever, they say drinking coffee in pregnancy may be associated with harms, and may be linked to a very small increased risk of fracture in women.

The included studies used mainly observational data, providing lower quality evidence, so no firm conclusions can be drawn about cause and effect, but their findings back up other recent reviews and studies of coffee intake. As such, they say, excluding pregnancy and women at risk of fracture, "coffee drinking appears safe within usual patterns of consumption" and they suggest that coffee could be safely tested in randomised trials.

To better understand the effects of coffee consumption on health, a team led by Dr Robin Poole, Specialist Registrar in Public Health at the University of Southampton, with collaborators from the University of Edinburgh, carried out an umbrella review of 201 studies that had aggregated data from observational research and 17 studies that had aggregated data from clinical trials across all countries and all settings. (Original study.)

There are a number of professions where there is an elevated risk for getting chronic obstructive pulmonary disease (COPD) from all the vapors, gases, dust, fumes, and chemicals (all irritants) that one inhales - such as welders, coal miners, cotton textile workers, construction, farmers, even hairdressers. Now a study suggests that nurses who use disinfectants at least once a week are also at higher risk for COPD. The specific disinfectants associated with COPD are glutaraldehyde, bleach, hydrogen peroxide, alcohol, and quats (quaternary ammonium compounds).

From Medscape: Exposure to Disinfectants Linked to COPD

The risk for chronic obstructive pulmonary disease (COPD) is higher in those who use disinfectants at least once a week than in those who do not, a preliminary observational study of a large cohort of female nurses in the United States reveals. 

For their study, Dr Dumas and her colleagues analyzed data from the Nurses' Health Study II. From 2009 to 2017, participants completed a survey every 2 years. ..... And they used the job-task exposure matrix to evaluate seven major disinfectants: formaldehyde, glutaraldehyde, hypochlorite bleach, hydrogen peroxide, alcohol, quaternary ammonium compounds (or quats), and enzymatic cleaners.

In the cohort of 55,185 women who were nursing in 2009, 663 reported incident physician-diagnosed COPD during the follow-up period. The team found an association between incident COPD and high-level exposure to glutaraldehyde, bleach, hydrogen peroxide, alcohol, and quats. Of the nurses diagnosed with COPD, 37% reported the weekly use of disinfectants to clean surfaces, and 19% reported weekly use to clean instruments. Regression models demonstrated that the risk for COPD was 22% higher for nurses who cleaned instruments, and 32% higher for nurses who cleaned surfaces.

We've been aware of the association between disinfectants and asthma for some time, she told Medscape Medical News.... There's no easy solution, Dr Dumas acknowledged. "Protection from infection is important, but so is the health of workers." Green products might be one solution, "but we're not sure of their effect on health either. Just because they're natural, doesn't mean they're safe; they can have allergens." Another solution could be ultraviolet light, as previously reported by Medscape Medical News.

This was a "well-performed study," said Lidwien Smit, PhD, from the University of Utrecht in the Netherlands. "I just wonder about the pathology, and how it influences the microbiome. Disinfectants are meant to kill off bacteria, but if you're exposed to large concentrations, you're also inhaling them, which could affect your airway microbes," she explained. In fact, disinfectants could play a role in killing off bacterial communities in the airways that are responsible for "immune homeostasis" and keep users healthy, she added. If that immune balance gets disturbed, it might have an influence on a person's reaction to pathogens or inflammation. 
Chest X-ray of person with COPD. Credit: Wikipedia

An interesting possibility - that taking supplements of  a type of vitamin E known as gamma tocopherol may reduce the inflammation of the airways common in asthma patients – eosinophilic inflammation.

Note that these findings were from a preliminary study of 15 people with mild asthma, done by researchers at the Univ. of North Carolina. Now larger and longer studies need to be done, especially to make sure that side-effects and an increased risk for hemorrhagic stroke won't occur with gamma tocopherol, as it does for the other form of vitamin E (alpha tocopherol) commonly found in supplements. From Medical Xpress:

Can asthma be controlled with a vitamin supplement?

The shortness of breath experienced by the nearly 26 million Americans who suffer from asthma is usually the result of inflammation of the airways. People with asthma typically use albuterol for acute attacks and inhaled steroids to limit chronic inflammation. Both medications come with side effects. But what if it was possible to keep asthma under control by changing one's diet or taking a vitamin supplement? It may happen sooner than you think.

Preliminary research results from the UNC School of Medicine indicate that a type of vitamin E known as gamma tocopherol may reduce eosinophilic inflammation – a kind of airway inflammation common in asthma patients. The results were published in the Journal of Allergy & Clinical Immunology.

"We started looking into vitamin E because epidemiologic data suggested that people with high amounts of vitamin E in their diet were less prone to asthma and allergic disease," said Michelle Hernandez, MD, professor of pediatrics and senior author of the study.  There are several different isoforms of vitamin E. The type commonly found in vitamin supplements – alpha tocopherol – has been studied previously, but the results suggested that alpha tocopherol was not particularly effective. Even worse, the alpha isoform seemed to be associated with an increased risk for hemorrhagic stroke.

So UNC researchers took a different tack and asked whether the kind of vitamin E being used might have an effect on the outcome. They began looking more closely at gamma tocopherol, the type of vitamin E commonly found in a diet rich in nuts and nut oil. .... "While the alpha isoform does have antioxidant activities, gamma tocopherol has both an antioxidant and a very unique anti-inflammatory action as well," she said "That anti-inflammatory effect is what we think made the difference in this study."

Participants in the study were randomized into two groups that received either gamma tocopherol supplement or a placebo for two weeks. At the end of that period, they were asked to cough up sputum..... After a three week "washout period" where they took nothing, subjects were placed in the other group: if they took the supplement for the first two weeks, they took a placebo for the second period.

"The advantage of a cross-over design like this is that we are able to compare the subjects to themselves," said Burbank. "And what we found is that when people were taking the vitamin E supplement, they had less eosinophilic inflammation." In addition to decreased inflammation, those who were taking vitamin E were also found to have lower levels of proteins called mucins, which affect the stickiness of mucus. Mucins are often elevated in asthmatics.

The following study was done in England, but the results should be taken seriously and may (probably) apply to the US also - painted and enameled glassware ("externally decorated glassware") may contain high levels of lead and cadmium. The researchers found that more than 70% of the products (52 out of 72) tested positive for lead, and the metal was found in all colors, including the decorated gold leaf of some items. A similar number (51 out of 72) tested positive for cadmium, with the highest concentrations usually encountered in red enamel.

They found this in products manufactured both in Europe and China - which is why I think the results apply to painted or decorated glassware in the USA also. It probably also applies to some (many?) painted ceramics. So beware!  If you use painted or enameled glassware, you are at increased risk for ingesting lead and cadmium, both of which are linked to health problems - especially for developing fetuses and children. The best safe level of each is zero. The researchers mention that there are newer alternatives that are safe (lead and cadmium free). From Science Daily:

Drinking glasses can contain potentially harmful levels of lead and cadmium

Enameled drinking glasses and popular merchandise can contain potentially toxic levels of lead and cadmium, a study has shown. Researchers at the University of Plymouth carried out 197 tests on 72 new and second-hand drinking glass products, including tumblers, beer and wine glasses, and jars.

They found lead present in 139 cases and cadmium in 134, both on the surface of the glasses and, in some cases, on the rims, with concentrations of lead sometimes more than 1000 times higher than the limit level. Tests showed that flakes of paint often came away from the glass under when simulating sustained use, indicating the substances could be ingested over a prolonged period.

The study, published in Science of the Total Environment, analysed a range of glassware using portable x-ray fluorescence (XRF) spectrometryMore than 70% of the products (52 out of 72) tested positive for lead, and the metal was found in all recorded colours, including the decorated gold leaf of some items. A similar number (51 out of 72) tested positive for cadmium, with the highest concentrations usually encountered in red enamel.

The lead concentrations ranged from about 40 to 400,000 parts per million (ppm), while quantities of cadmium ranged from about 300 to 70,000 ppm. According to the US Office of Environmental Health Hazard Assessment, the limit levels for the externally decorated lip area of drinking glass are 200 ppm and 800 ppm respectively.

In the research, Dr Turner highlights that the Federation of European Screen Printers Associations says organic inks are becoming more popular than metallic pigments because of environmental concerns, and that such inks were evident on a number of newly-purchased products which proved negative for lead and cadmium.

He also says that additional analyses confirmed that hazardous elements are also used to decorate a wider range of consumer glassware that has the potential to be in contact with food, including the exteriors of bottles for the storage of beer, wine or spirits, the external text and logos on egg cups, jugs and measuring cups, and the undersides of coasters and chopping boards. "Given that safer alternatives are available to the industry, the overall results of this study are both surprising and concerning," Dr Turner added. "Why are harmful or restricted elements still being employed so commonly to decorate contemporary glassware manufactured in China, the European Union and elsewhere? " [Original study.]

The following is a nice article about a recently published study finding a link between some bacteria commonly found in the mouth and inflammatory bowel diseases (IBD). The researchers found that some strains of oral bacteria are also found in the gut of people with inflammatory bowel diseases.

They theorize that these bacteria make it down to the gut when saliva is swallowed - and for susceptible people this may trigger inflammatory disease. They did a number of experiments to determine that the antibiotic-resistant, inflammation causing species of Klebsiella pneumoniae and Klebsiella aeromobilis could be triggering IBD. These bacteria are able to replace normal colon microbes after antibiotic therapy.

However, it must be noted that other studies also find other microbial differences among those with IBD and healthy people - e.g. low or absent levels of Faecalibacterium prausnitzii, and even fungal and viral differences. From Harvard Magazine:

Gut Health May Begin in the Mouth

Chronic gastrointestinal problems may begin with what is in a patient’s mouth. In a study published Thursday in Science, an international team of researchers—including one from Harvard—reported on strains of oral bacteria that, when swallowed in the 1.5 liters of saliva that people ingest every day, can lodge in the gut and trigger inflammatory bowel conditions like Crohn’s disease and ulcerative colitis.

“For some time now, we’ve noticed that when we look at the microbiome of patients with inflammatory bowel disease, or IBD, we’ve found microbes there that normally reside in the oral cavity,” says study co-author Ramnik Xavier, chief of gastroenterology at Massachusetts General Hospital (MGH)....

Simultaneously, “There’s always been this other search, asking, ‘Are there pathobionts?’”—in other words, microbes that live innocuously in one part of the body but can turn pathogenic when moved to another. “For some time we have been looking for pathobiont organisms for Crohn’s and colitis.”

The researchers believe they have found them: two strains of Klebsiella bacteria, microbes commonly found in the mouth. ....the researchers pinpointed a strain of Klebsiella pneumoniae as the trigger for the immune response. A subsequent experiment using samples from two ulcerative colitis patients turned up another inflammation-causing strain, of Klebsiella aeromobilis

Checking databases of thousands of IBD patients at MGH and the Hospital of the University of Pennsylvania, Xavier and others found that people with inflammatory bowel conditions had significantly more Klebsiella bacteria in their gut microbiome than healthy patients did. Most likely, he explains, oral bacteria, including Klebsiella, traffics through everyone’s gut in the saliva we swallow. Usually it passes through harmlessly; but in people with a genetic susceptibility to IBD that alters the gut microbiome, the Klebsiella has a chance to take hold in the intestine and proliferate, inducing an immune response that causes the disease. 

And there is another twist: Klebsiella bacteria are often extremely resistant to multiple antibiotics. That explains, Xavier says, “why antibiotics have limited value in treating patients with Crohn’s disease and ulcerative colitis....  “Because we also showed in a 2014 paper that patients who took antibiotics—and this has been seen in the old clinical data accumulated before the microbiome was even examined in IBD—that patients who took antibiotics early in the disease had more complicated outcomes.” 

Klebsiella  pneumoniae Credit: Wikipedia


Another interesting theory about dyslexia, as well as a great treatment possibility. It is unknown if the study results will hold up with more research (after all, only 60 people were in the study - 30 with dyslexia and 30 without), and whether their suggested treatment really works for larger groups of dyslexics. But what if it helps?

Their main finding is that those who don't have dyslexia have  "asymmetry" in the light-receptor cells in the center of the eye, while dyslexics have symmetry which leads to the brain producing confusing mirror images of letters (e.g."b" and "d"). The researchers conclude that: "the lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities in people with a normal ocular status but with dyslexia". They found that a flashing LED lamp ("pulse-width modulation light-emitting diode") suppressed the mirror images in those with dyslexia and they could read normally ("restores reading skills"). So this research is definitely worth following. From Medical Xpress:

Scientists may have found a cause of dyslexia

A duo of French scientists said Wednesday they may have found a physiological, and seemingly treatable, cause for dyslexia hidden in tiny light-receptor cells in the human eye. In people with the reading disability, the cells were arranged in matching patterns in both eyes, which may be to blame for confusing the brain by producing "mirror" images, the co-authors wrote in the journal Proceedings of the Royal Society B. In non-dyslexic people, the cells are arranged asymmetrically, allowing signals from the one eye to be overridden by the other to create a single image in the brain.

It offers a "relatively simple" method of diagnosis, he added, by simply looking into a subject's eyes. Furthermore, "the discovery of a delay (of about 10 thousandths of a second) between the primary image and the mirror image in the opposing hemispheres of the brain, allowed us to develop a method to erase the mirror image that is so confusing for dyslexic people"—using an LED lamp.

Like being left- or right-handed, human beings also have a dominant eye. As most of us have two eyes, which record slightly different versions of the same image, the brain has to select one of the two, creating a "non-symmetry." Many more people are right-eyed than left, and the dominant eye has more neural connections to the brain than the weaker one. Image signals are captured with rods and cones in the eye—the cones being responsible for colour. The majority of cones, which come in red, green and blue variants, are found in a small spot at the centre of the cornea of the eye known as the fovea. But there is a small hole (about 0.1-0.15 millimetres in diameter) with no blue cones.

In the new study, Ropars and colleague Albert le Floch spotted a major difference between the arrangement of cones between the eyes of dyslexic and non-dyslexic people enrolled in an experiment. In non-dyslexic people, the blue cone-free spot in one eye—the dominant one, was round and in the other eye unevenly shaped. In dyslexic people, both eyes have the same, round spot, which translates into neither eye being dominant, they found.

Dyslexic people make so-called "mirror errors" in reading, for example confusing the letters "b" and "d". ....The team used an LED lamp, flashing so fast that it is invisible to the naked eye, to "cancel" one of the images in the brains of dyslexic trial participants while reading. In initial experiments, dyslexic study participants called it the "magic lamp," said Ropars, but further tests are required to confirm the technique really works. [Original study.]


Cross-section of the human eye. Credit: Wikipedia